Machine for manufacturing hollow core structures of concrete and the like

ABSTRACT

A mould has a removeable wall so that concrete can be poured therein. A plurality of mould core assemblies are insertable in the mould and are surrounded by the concrete mix. Fluid under pressure expands elastic sleeves surrounding the mould cores and thus compresses the concrete against the walls of the mould. Water extraction members are also insertable in the mould and are also surrounded by concrete. These members may either be separate from or formed part of the mould core assemblies. Filtering material surrounds these members so that free water expressed by the compression of the concrete can drain or be evacuated by these members thus causing the concrete to be compressed into a semi-rigid and relatively dry state so that it can be removed from the mould. Concrete structures formed this way are accurate as to all external dimensions.

Sellers et al.

Inventors: Frederick Sellers; Marvin Thorsteinson; Ernst Martens, all of Winnipeg, Manitoba, Canada [73] Assignee: Spiroll Corporation Ltd., Winnipeg,

Manitoba, Canada [22] Filed: Oct. 10, 1972 [21] Appl. N0.: 296,189

Related US. Application Data [63] Continuation-in-part of Ser. No. 243,159, April 12,

1972, abandoned.

[52] US. Cl 425/84, 249/65, 249/113 [51] Int. Cl. 1328b 21/36 [58] Field of Search 249/65, 113; 425/84, 85

[56] References Cited UNITED STATES PATENTS 3,667,880 6/1972 Malet et a1 425/84 X 2,977,658 4/1961 Smith et a1 249/65 2,625,728 1/1953 Eschenbrenner.. 425/85 3,524,232 8/1970 Shoe 249/65 X [451 May 7,1974

Smith 249/65 Primary ExaminerR. Spencer Annear Attorney, Agent, or Firm-Stanley G. Ade

[57] ABSTRACT A mould has a removeable wall so that concrete can be poured therein. A plurality of mould core assemblies are insertable in the mould and are surrounded by the concrete mix. Fluid under pressure expands elastic sleeves surrounding the mould cores and thus compresses the concrete against the walls of the mould. Water extraction members are also insertable in the mould and are also surrounded by concrete. These members may either be separate from or formed part of the mould core assemblies. Filtering material surrounds these members so that free water expressed by the compression of the concrete can drain or be evacuated by these members thus causing the concrete to be compressed into a semi-rigid and relatively dry state so that it can be removed from the mould. Concrete structures formed this way are accurate as to all external dimensions.

10 Claims, 14 Drawing Figures PATENTEDHAY 1 M smssla SHEET 5 OF 5 MACHINE FOR MANUFACTURING HOLLOW CORE STRUCTURES OF CONCRETE AND THE LIKE This invention relates to new and useful improvements in devices for the manufacture of hollow core structures such as wall panels, floor or roof panels, columns, stairs or other components and this application constitutes a continuation-in-part of Ser. No. 243,159, filed Apr. 12, 1972 now abandoned.

BACKGROUND OF THE INVENTION Although the present description refers to such demethod of production include the fact that dimensionalstability cannot be controlled inasmuch as the concrete mass is obviously of a smaller volume when the water has been voided. Secondly, excessive pressures are required on the upper panel particularly when relatively large concrete forms are being produced and. this together with the fact that the dimensions are difficult to control, leads to uncertainty as to the thickness of concrete as for example, between the cores and the outer surfaces. This fault is particularly noticeable if reinforcing of any kind is introduced into the form prior to compression.

As an example, a panel may be provided with a plurality of longitudinally extending rectangular or circular cross sectional cores with reinforcing wire or cables being embedded in the concrete surrounding these cores and conventionally, the thickness of concrete in some areas may be as little as one or two inches. It will .therefore be appreciated that any variation in this thickness could seriously weaken the finished structure.

SUMMARY OF THE INVENTION The present invention overcomes these disadvantages by utilizing a different principal.

The core forms are insertable within the mould and are covered with a membrane or cover made of rubber or the like, sealed at the ends. Pressure is introduced within the interior of the core form and passes through apertures in the form to expand the membrane or rubber cover outwardly thus applying the necessary pressure internally to void the water. Means are also provided to allow the water to flow outwardly from the form as the pressure is applied and, in one embodiment, takes the form of longitudinally extending evacuation tubes or members which are multi-apertured and are covered with a filter medium in order to prevent washout of cement or the like. This method ensures that the external dimensions are always the same and also permits a finished surface to be provided to the structure. The evacuation of the water, caused by the expansion of the membranes or rubber covers around the core .forms, is assisted by vibrators operating at either high or low frequency which permits the evacuation of sufficient water to enable the concrete to set up" rapidly so that it can be removed from the mould for curing purposes.

The core forms can be of any convenient or desired shape such as rectangular in cross section or circular in cross section and window and/or door frames may be insertable within the moulds as desired. Furthermore it is relatively easy to reinforce the structure either by means of wire mesh, steel rods, or pretensioned steel wires.

The preferred embodiment comprises the core forms of the previous embodiment but with the water evacuation means incorporated therewith so that sufficient rigidity is provided to the core forms and the water evacuation means. I

With the foregoing objects in view, and such other or further purposes, advantages or novel features as may become apparent from consideration of this disclosure and specification, the present invention consists of the inventive concept which is comprised, embodied, embraced, or included in the means, method, process, product, construction, composition, arrangement of parts, or new use of any of the foregoing, herein exemplified in one or more specific embodiments of such concept, reference being had to the accompanying FIG. 1 is a top plan view of the invention with the upper structure removed for clarity and showing the mould cover removed.

FIG. 2 is a section along the line 22 of FIG. with the superstructure in place.

FIG. 3 is a sectional view substantially along the line BB of FIG. 1.

FIG. 4 is an enlarged section of one of the evacuation tubes along the line C-C of FIG. 1.

FIG. 5 is an enlarged cross-sectional view of one of the core forms substantially along the line D-D of FIG. 1.

FIG. 6 is an enlarged isometric view of one of the evacuation tubes.

FIG. 7 is a fragmentary enlarged view of one of the core forms. 1

FIG. 8 is a fragmentary cross-sectional view taken longitudinally of one of the mould cores.

FIG. 9 is an isometric view of a combination core form and water evacuation means of the preferred embodiment. 1

FIG. 10 is an isometric view of the water evacuation means per se with the two halves separated for clarity.

l but FIG. 11 is a longitudinal section of FIG. 9.

FIG. 11A is a fragmentary partial section of one end of one-half of the water evacuation means.

FIG. 12 is an isometric view of an alternative cross sectional configuration of FIG. 9.

FIG. 13 is an end view, in larger scale of a preferred embodiment of the water evacuation means.

In the drawings like characgers of reference indicate corresponding parts in the different figures.

DETAILED DESCRIPTION Proceeding therefore to describe the invention in detail, reference character 10 illustrates generally supporting structure which consists of the braced base 11,

3 upwardly extending vertical members 12 and upper members 13.

In the present invention, a concrete panel 14 is being formed but it.will of course be appreciated that the mould for forming the structure will vary in shape depending upon the external configuration of the structure being formed.

In this particular embodiment, a mould base plate 15 is supported upon the base supporting structure 11 and side members 16 extend around all four sides of the base.

A top plate 17 is secured to transverse girder construction 18 which is adapted to be moved vertically up and down the vertical members 12 by hydraulics or cables (not illustrated). Alternatively, of course, the

' lower plate 15 could move up and down with the top plate stationary.

When the top plate 17 is in the lowermost position it engages the upper edges of the sides 16 and encloses after the formation of the concrete structure 14 as will hereinafter be described. The mould is preferably lined with a release agent either in theform of a semi-liquid or an elastomeric membrane.

Lower vibrators collectively designated 19 are situatcd beneath the mould base 15 and within the base supporting structure 11 and are conventional in construction. These vibrators are electromagnetically connected to the base as indicated in FIG. 3 by reference character 20. However, other methods of connection can, of course, be utilized. v

A material hopper or carrier 21 is mounted upon rails 22 extending to one side of the supporting structure 10 and these rails extend upon each side of the mould as indicated in FIGS. 1 and 2 so that the hopper or material supply device can be moved across the open mould and can deposit concrete mix or the like within the mould as will hereinafter be described.

A plurality of mould cores collectively designated 23 are inse rtable within the side plates 16 of the mould and FIG.. 3 shows details of this structure/The mould cores are secured to transverse members 24 which are wheel supported as at 25 upon rails 26 situated on each side of the supporting structure .10. Guide wheels 26 are provided adjacent the side walls 16 of the mould to support the cantilever ends of these core moulds. Hydraulic means or the like (not illustrated) enables these core moulds to be moved inwardly and outwardly of the mould in the direction of double headed arrow 27, it being understood that apertures (not illustrated) are provided in the mould sidesl6 to permit this entry and withdrawal.

Also mounted upon the member 24 is a plurality of evacuation tubes collectively designated 28 and these are also supported upon the guide wheels or rollers 26' and can be inserted or withdrawn into or from the mould together with the core moulds 23, apertures also being provided within the side walls 16 of the mould.

Reference to FIGS. 4 to 8 inclusive show details of these two components 23 and 28.

Dealing first with the core moulds 23, in this embodiment they consist of metal hollow cores substantially rectangular in cross sectional configuration but being provided with rounded corners 29. However, it will be appreciated that these core moulds can have any desired cross sectional configuration.

Both ends 30 are sealed and a plurality of apertures 31 is formed through the four walls of the core mould as clearly shown in FIGS. 5 and 7.

An impermeable flexible sleeve 32 preferably made of rubber or neoprene or the like, surrounds the core mould as shown and is sealed to the mould at either end by conventional means. For example, this sealing may take the form of a combination adhesive and metal clamp] A conduit 13 engages one end wall 30 and is connected to the interior of the mould core. These conduits are also connected to a source of pressure either hydraulic or pneumatic (not illustrated) which, when activated, causes pressure to expand the rubber or neoprene sleeve outwardly from the core walls and apply pressure to the concrete surrounding same.

The evacuation tubes or members 28 are shown in FIGS. 4 and 6. These take the form of rectangular elongated hollow sections having dimensions considerable smaller than the core forms 23. They are shown as being rectangular in cross section but, of course, they can be circular if desired. These members 28 are provided with perforated walls as indicated by reference character 34 and these walls together with the perforations are covered by filter paper 35 prior to use. A

transverse web 36 is also provided for strengthening purposes.

The evacuation members also engage one or both walls of the mould depending upon the design and they are tapered longitudinally as shown in FIG. 6 to facilitate withdrawal from the mould after compaction of the concrete has taken place.

It is also desirable that the mould wall apertures (not illustrated) which receives these members 28 are dimensioned so that the members are in wedging engagement when inserted into the mould. By the same token the apertures provided for the engagement of the core moulds 23 should be provided with some form of rub ber seal (not illustrated) in order to prevent leakage occurring past the core moulds externally of the mould when compression is applied to the concrete. 1

In operation, the core moulds 23 and the evacuation members 28 are inserted through the side walls 16 of the mould as hereinbefore described and the upper plate 17 is moved to the uppermost position as shown in FIG. 2.

The concrete or other material conveyor 21 is then moved across the open underside of the mould depositing the required amount of .concrete in the mould to completely fill same. During this process, the vibrators 19 should be actuated to facilitate the flowing of the concrete below and around the members 23 and 28. The upper surface of the concrete mix is screeded level with the upperedges of the sides of the mould and the hopper 21 is withdrawn to one side.

.The upper plate 17 is then lowered and held firmly in position either by hydraulics or clamps (not illustrated). In this connection further vibrators are provided above the upper plate as indicated schematically by reference character 37.

In the event that the mass of the mould frame becomes too great to make it practical to supply the vibrational energy to the material in the mould or for any other reason, the energy would be supplied by vibrators attached to diaphrams on the ends of the conduits 33 and transmitted to the mix in the mould through the water in the conduits.

Another method would be to supply the energy by means of transducers placed inside the conduits supplying the energy directly to the water and through the conduit to the mix surrounding it.

Pneumatic or hydraulic pressure is then applied through the conduits 33 which in turn applies pressure via the flexible sleeve 32, radially or externally of the mould cores and causes the excess water in the concrete to migrate to the evacuation tubes 28. The water passes through the filter paper 35 and outwardly of the open ends of these members 28 which of course are external of the mould walls. Sufficient pressure is applied to the expanding rubber or neoprene covers 32 to evacuate the required amount of water and to supply sufficient compaction to the concrete.

When this state has been reached, the vibrator may be switched off; the core moulds 23 and the evacuation vmembers 28 are then withdrawn through the sides of the mould and the upper plate 17 moved upwardly; The

sides may also be disconnected so that the mould base together with the formed panel 14 may be moved to one side of the machine and stored within storage racks collectively designated 38 situated on one side of the machine. In this connection rollers 39 or the like may be provided.

Reference to FIG. 1 will show the window frames 40 have been placed within the mould, said window frames should of course preferably be braced to withstand the moulding pressure. Under these circumstances some of the members 23 and 28 are relatively short and engage the mould walls from either side with the inner ends terminating short of the frames 40. Similarly, door frames (not illustrated) may be inserted within the mould.

From the foregoing, it will be appreciated that external dimensions are strictly controlled by the walls ofthe mould and that the pressure will enable any pattern or surface to be formed on the external surfaces of the panel.

The energy applied to the mix by the external vibrators attached to the mould case top and bottom or internal vibration from within the conduit 33, permits the movement of the material in the mould to compensate for the release of the water so that complete compaction of the material results when all the free water has been released.

The results of the combined pressure and vibrational energy produces a solid casting dry enough to keep its shape during the removal of the core, evacuation components 23 and the mould casing.

To facilitate withdrawal of the core moulds 23 after compaction, negative pressure is applied to the core which causes the cover 32 to collapse onto the walls of the core thus permitting same to be withdrawn without damage occurring to the concrete surrounding same.

The filter paper 35 prevents cement and fines from being removed with the water and this filter paper can stay in the casting after removal of the elements 28.

If desired, vacuum can be applied to the evacuation tubes to facilitate withdrawal of the water although this is not normally necessary.

The mould frame 16 can be made rigid enough to support prestressed steel wire if necessary or steel mesh reinforcing can be introduced in the areas above and below the core moulds prior to filling with concrete.

By the same token the mould can be used to support any steel fasteners or hardware which needs to be incorporated into the finished panel.

Any of the mould surfaces, particularly the upper and lower surfaces can be provided with vacuum connections which will hold the architectural uneveness of the panel if same is desired, until the concrete is set and ready to be removed from the mould.

Summarizing, the panel or the like is formed within a rigid mould by expanding or applying pressure to the concrete internally and voiding the water through members provided thus giving dimensional stability and accurate reproduction time after time to the panels or objects being produced.

FIG. 8 is a fragmentary cross sectional view taken longitudinally of one of the mould cores.

This view shown in FIG. 8, shows one method of sealing the flexible sleeve 32 to the mould core around the ends thereof.

In this particular embodiment, the end walls 30 are illustrated and the upper wall extends beyond these end walls and slopes downwardly at the inner end 41 thereof and is provided with an annular groove or trough 42 terminating with a vertical wall 43.

Situated within this groove or trough 42 is an annular, inflatable tube 44 having an inflating nozzle 46 extending exteriorally of the mould and the end of the sleeve 32 passes over this inflatable tube 44 as clearly shown. An annular clamping ring 47 is seated upon the area of the envelope above the inflatable tube 44 and the inner wall 16 of the mould is provided with an annular horizontal flange portion 48 all of which is clearly shown. The sloping portions 41 permit the mould cores to be withdrawn and inserted as hereinbefore described At the opposite end of the mould core and above the wall 30 is an annular U-shaped cross sectional ring 49 carrying an inflatable annular tube 50 therein which registers above the envelope 32 when the cores are inserted within the mould. This may be secured to the mould wall 16 by bolts 51 but alternatively, can be secured to the transverse members 24 which insert and withdraw the mould cores in this embodiment.

This inflatable tube 50 is also provided with an inflating nozzle 46 extending through the annular ring 49.

In operation, the mould cores and envelopes 32 are inserted into position whereupon the tubes 44 and 50 are inflated to a predetermined pressure thus causing them to clamp'the flexible envelope 32, to the mould cores around the ends thereof. This provides an effective pressure seal between the sleeve or envelope 32 and the ends of the mould core tubes 29.

In both cases the inflatable tubes, when inflated, react within the restricted spaces provided by the structure hereinbefore described.

The inflated tube 50 reacts upon the outside of the envelope 32 pressing it onto the outside of the mould core to provide the seal whereas the inflatable tube 44 develops its seal through pressure upwardly against the underside of the envelope 32 and against the annular ring 47.

A further concept contemplates the use of a foaming insulation agent which may be layered between the upper and lower walls of the mould and within the concrete or may be placed in a layer on the bottom of the mould, concrete poured in and then a further layer placed'on the upper surface of the concrete.

When the mould is closed, chemical action may be initiated either by external heat or by heat generated within the concrete thus causing the material to foam and increase in volume. This would provide the necessary pressure to express the excess water assisted by the vibrators. I

FIGS. 9 to 12 inclusive show the preferred embodiment of the core forms and water evacuation means which are combined in this embodiment in order to provide cantilever stability to the components.

In relatively large panels or the like, there is the possibility that the evacuation tubes 28 may be deflected by the pressures of the concrete surrounding same and the preferred embodiment prevents this from occurring.

The core form collectively designated 23 is similar in construction and operation to the core form hereinbefore described although in the present embodiment, it is shown as being substantially cylindrical in configuration. It is covered by the impermeable, flexible sleeve 32 as in the previous embodiment and conduit 33 is connectable to a source of fluid pressure as hereinbefore described.

The water evacuation means collectively designated -28A comprises two half components 52 one upon each side of the core mould 23.

Each component or half 52 consists ofa curved inner wall 53 having a' curvature similar to the curvature of the mould 23.

A curved outer wall 54 having a smaller radius than the wall 53 is secured to the edges of the inner wall as at 55, as by welding or the like thus providing a longitudinally extending spaced chamber 55 between the inner and outer walls as clearly shown in the drawings. The ends 56 and 57 are closed and drainage conduits 59 extend through the end walls 57 and are situated adjacent the lower side thereof so that water may drain by gravity .or, alternatively, may be withdrawn by vacuum means as hereinbefore described.

The outer wall is apertured as at 60 and the entire combined member consisting of the mould 23 and the evacuation components 28A are covered by filter paper similar to fllter paper 34 described in the previous embodiment.

Means are provided to hold the two halves 52 inclose relationship upon the flexible membrane 22. This means may either take the form of heavy duty rubber bands shown in phantom by reference character 61 in FIG. 9 or, alternatively, by leaf springs 62 shown in the cross sectional view illustrated in FIG. 11.

An end plate 63 is secured to the end 64 of the mould form 23 from which the conduit 33 extends and the halves 52 are loosely connected to this end plate by means of the conduits 59 extending through apertures in this end plate and being secured by hairpin spring pins or clips 65 engaging annular grooves 66 formed in the conduits 59 as shown in the detail illustrated in FIG. 11A.

The leaf spring 62 curveinwardly at the ends as illustrated by reference character 67 and engage through apertures 68 within the end plate 63. Wedges 69 are then driven into the apertures thus biassing the spring leaves 62 inwardly so that the innermost curved ends 67 engage the inner curved walls 57 of the halves 52 and force these halves into close contact with the flexible sleeve 32 as shown in FIG. 11. When the sleeves are inflated, they move the halves outwardly but these halves are still maintained in close contact with the sleeve by means of the springs 62.

FIG. 12 shows an alternative embodiment in which the cross sectional configuration of the halves 52 is of a greater curvature than the halves shown in FIG. 9 thus giving a substantially oval configuration to the overall component.

Maintaining the halves 52 in close contact with the mould cores 23 gives cantilever support to the halves and prevents them being deflected by the pressure of concrete during the forming operation.

It will also be noted that the cross sectional configuration of the combination mould cores 23 and water extracting means 28A tapers from the end plate 63 thereof to the distal ends thus facilitating withdrawal after the concrete has been compacted and the water has been extracted.

FIG. 13 shows the preferred embodiment of the water evacuation assembly around the mould core 23.

Instead of using the relatively heavy rubber sleeve 32, a relatively thin latex sleeve 32A, which is easily formed or extruded, is slipped over the mould core 23. The water evacuating means 288 comprises two halves or components 52A, one upon each side of the core 23. Each half has curved inner wall or base portion or segment 53A having a curvature similar to the curvature of the mould core 23.

A curved outer wall or segment 54A is provided, with flanged sides 54B stepped inwardly which register upon the sides of the inner wall thus maintaining the outer wall spaced from the inner wall in order to provide a spaced chamber 55A therebetween. The outer wall is perforated as at 60A similar to the previous embodiment.

The sleeve 32A requires reinforcement over the areas between the water evacuating halves 288 because the relatively thin nature of the extruded latex sleeve tends to balloon outwardly under fluid pressure. To this end there is provided reinforcing latex webs 70 one upon each side of the core 23. Each of these webs has a longitudinally extending bead 71 formed along each edge thereof. This bead can take the form of a metal rod adhesively secured within the edges or, alternatively, can be a latex bead formed on the edge of the latex sheet during the extrusion of other forming process.

The edges are engaged between the edges of the inner wall 53A and the side flanges 54B of the outer walls, with the bead being in the chambers 55A as shown thus preventing the webs from becoming disengaged from between the walls. The inner and outer walls are clamped together by means of screws or rivets 72 with bushings 73 maintaining the spaced apart relationship of the inner and outer walls 52A and 53A.

End pieces are placed in each end prior to clamping the walls together, one of which has water drain tubes, (not illustrated) similar to the tubes in the previous embodiment.

The double thickness of latex or the like over the areas 74 prevents ballooning and enables a more economical structure to be provided which is easily disassembled for cleaning and maintenance purposes.

Finally it should be noted that although the present embodiments are directed to the formation of substantially rectangular concrete panels or the like, nvertheless any suitable configuration can be formed depending upon the shape of the moulds. Various modifications may be constructed or performed within the scope of the inventive concept disclosed Therefore what has been set forth is intended to illustrate such concept and is not for the purpose of limiting protection to any herein particularly described embodiment thereof,

What we claim as our invention is:

1. A device for the manufacture of hollow cored structures of concrete and the like in conjunction with a source of fluid pressure; comprising in combination a mould, detachable means to provide access to said mould whereby concrete mix can be poured therein, vibration means associated with said device for assisting in the compacting and dispersion of said mix within said mould, at leastone core form in said mould, means to engage and retract said core form into and out of said mould, at least one water extraction component in said mould and means to engage and to retract said water extraction component into and out of said mould, said core form and said water extraction component forming a composite unit, said component being in two halves closely surrounding said core form and means resiliently securing said halves to said core form.

2. The device according to claim 1 in which said core form comprises a hollow, elongated member, means to support said member by one end thereof, the ends of said member being closed, the wall portion between said ends of said members being apertured and a flexible, resilient membrane covering said wall portion and being sealed to said wall portion at each end thereof,

and means connecting the interior of said core form with said source of fluid pressure whereby said membrane may be expanded away from said member.

3. The device according to claim 1 in which said water extraction component comprises a substantially elongated hollow member closed at each end thereof and having a perforated wall portion between said ends, means mounting said component by one end thereof, and a drain conduit in said one end extending externally of said mould, and filtering means surrounding said perforated wall portion to prevent fines and sand from entering said perforated wall portion.

4. The device according to claim 2 in which said water extraction component comprises a substantially elongated hollow member closed at each end thereof and having a perforated wall portion between said ends, means mounting said component by one end thereof, and a drain conduit in said one end extending externally of said mould, and fltering means surrounding said perforated wall portion to prevent fines and sand from entering said perforated wall portion.

5. The device according to claim l in which said core form includes a hollow, elongated member having closed ends and a substantially curved wall portion therebetween, each of said halves including an inner wall segment having a curvature similar to the curvature ofsaid wall portion and outer wall segment having a curvature with a radius less than the radius of said inner wall segment, said segments being joined along the upper and lower edges thereof thereby defining a chamber therebetween, the ends of said chamber being closed, said outer wall segment being multi-apertured to permit ingress of water to said chamber.

6. The device according to claim 5 which includes means to support said member by one end thereof, the ends of said member being closed, the wall of said member being apertured, a flexible, resilient membrane covering said wall and being sealed to said wall at each end thereof, and means connecting the interior of said core form with said source of fluid pressure whereby said membrane may be expanded away from said member, said means resiliently securing said halves'to said core including an end plate secured to said core portion at said one end thereof, means mounting said halves loosely by one end thereof to said end plate, and a pair of flat strip springs engaging apertures in said end plate and extending into said chamber, wedge means engaging said apertures in said end plate thus holding said springs biassed towards the inner walls of said halves thereby urging said halves against said membrane.

7. The device according to claim 1 in which said core form includes a hollow, elongated member having closed ends and a substantially curved wall portion therebetween, each of said halves including an inner wall segment having a curvature similar to the curvature of said wall portion, and an outer wall segment having a similar curvature to said inner wall segment, said outer wall segment having stepped flanges formed on the side edges registering upon the side edges of the inner wall segment to maintain said segments in spaced apart relationship thereby defining a chamber therebetween, means to clamp said segments together, and a flexible, resilient membrane clamped by the registering edges of said wall segments and extending between corresponding edges of said halves.

8. The device according to claim 3 in which said core form includes a hollow, elongated member having closed ends and a substantially curved wall portion therebetween, each of said halves including an inner wall segment having a curvature similar to the curvature of said wall portion, and an outer wall segement having a similar curvature to said inner wall segment, said outer wall segment having stepped flanges formed on the side edges registering upon the side edges of the inner wall segment to maintain said segments in spaced apart relationship thereby defining a chamber therebetween, means to clamp said segments together, and a flexible, resilient membrane clamped by the registering edges of said wall segments and extending between corresponding edges of said halves.

9. The device according to claim 2 in which said core form includes a substantially curved wall portion between said ends, each of said halves including an inner wall segment having a curvature similar to the curvature of said wall portion, and an outer wall segment having a similar curvature to said inner wall segment, said outer wall segment having stepped flanges formed on the side edges registering upon the side edges of the inner wall segment to maintain said segments in spaced apart relationship thereby defining a chamber therebetween, means to clamp said segments together, said flexible, resilient membrane being clamped by the reg istering edges of said wall segments and extending between corresponding edges of said halves.

H0. The device according to claim 4 in which said core form includes a substantially curved wall portion between said ends, each of said halves including an inner wall segment having a curvature similar to the chamber therebetween, means to clamp said segments curvature of said wall portion, and an outerwall segtogether said fl ibl resilient membrane being mem f a slmflar Curvature to aid mner wan clamped by the registering edges of said wall segments ment, said outer wall segment having stepped flanges formed on the side edges registering upon the side 5 and extending between corresponding edges of said edges of the inner wall segment to maintain said seghalvesments in spaced apart relationship thereby defining a I UI VITED STATES FATE OFFICE. CERTIFICATE OF CO RECTIQN Dated Mav- 7th, 1 274 Patent No. 3 3 091.513

Inventofla) Frederick Sellers et a1 It; iscertified char error apoea'ts in the above-idgnt1fied patent and that said Letgera Patent are hereby corrected as ahbwn below:

Priority is. olaimed from British Provisional Petent Ap'plicatio: 9356/71, filed April 14th, 1971 for Claims 1 to 6 inclusive.

Canadian uppl mentary Disclosure nc: 139,466 filed April 12th 1972 for Claims 7 to 10 inclusive. 1

g d ap ifsea led this 3rd day of 1 eem er i974.

- (SEAL) MCCOY g4. GLBS ON J R. Y I MARSHALL ms. Attestmg Officer; 7 V v Commissioner 'of P atents wonM Po-wsouo-em v 1 uncouu-ac Md-n1 Y 3 tumoovnppumvqmnmmmnmo-am 

1. A device for the manufacture of hollow coRed structures of concrete and the like in conjunction with a source of fluid pressure; comprising in combination a mould, detachable means to provide access to said mould whereby concrete mix can be poured therein, vibration means associated with said device for assisting in the compacting and dispersion of said mix within said mould, at least one core form in said mould, means to engage and retract said core form into and out of said mould, at least one water extraction component in said mould and means to engage and to retract said water extraction component into and out of said mould, said core form and said water extraction component forming a composite unit, said component being in two halves closely surrounding said core form and means resiliently securing said halves to said core form.
 2. The device according to claim 1 in which said core form comprises a hollow, elongated member, means to support said member by one end thereof, the ends of said member being closed, the wall portion between said ends of said members being apertured and a flexible, resilient membrane covering said wall portion and being sealed to said wall portion at each end thereof, and means connecting the interior of said core form with said source of fluid pressure whereby said membrane may be expanded away from said member.
 3. The device according to claim 1 in which said water extraction component comprises a substantially elongated hollow member closed at each end thereof and having a perforated wall portion between said ends, means mounting said component by one end thereof, and a drain conduit in said one end extending externally of said mould, and filtering means surrounding said perforated wall portion to prevent fines and sand from entering said perforated wall portion.
 4. The device according to claim 2 in which said water extraction component comprises a substantially elongated hollow member closed at each end thereof and having a perforated wall portion between said ends, means mounting said component by one end thereof, and a drain conduit in said one end extending externally of said mould, and fitering means surrounding said perforated wall portion to prevent fines and sand from entering said perforated wall portion.
 5. The device according to claim 1 in which said core form includes a hollow, elongated member having closed ends and a substantially curved wall portion therebetween, each of said halves including an inner wall segment having a curvature similar to the curvature of said wall portion and outer wall segment having a curvature with a radius less than the radius of said inner wall segment, said segments being joined along the upper and lower edges thereof thereby defining a chamber therebetween, the ends of said chamber being closed, said outer wall segment being multi-apertured to permit ingress of water to said chamber.
 6. The device according to claim 5 which includes means to support said member by one end thereof, the ends of said member being closed, the wall of said member being apertured, a flexible, resilient membrane covering said wall and being sealed to said wall at each end thereof, and means connecting the interior of said core form with said source of fluid pressure whereby said membrane may be expanded away from said member, said means resiliently securing said halves to said core including an end plate secured to said core portion at said one end thereof, means mounting said halves loosely by one end thereof to said end plate, and a pair of flat strip springs engaging apertures in said end plate and extending into said chamber, wedge means engaging said apertures in said end plate thus holding said springs biassed towards the inner walls of said halves thereby urging said halves against said membrane.
 7. The device according to claim 1 in which said core form includes a hollow, elongated member having closed ends and a substantially curved wall portion therebetween, each of said halves including an inner wall segment having a curvature similar to the curvature of said wall portion, and an outer wall segment having a similar curvature to said inner wall segment, said outer wall segment having stepped flanges formed on the side edges registering upon the side edges of the inner wall segment to maintain said segments in spaced apart relationship thereby defining a chamber therebetween, means to clamp said segments together, and a flexible, resilient membrane clamped by the registering edges of said wall segments and extending between corresponding edges of said halves.
 8. The device according to claim 3 in which said core form includes a hollow, elongated member having closed ends and a substantially curved wall portion therebetween, each of said halves including an inner wall segment having a curvature similar to the curvature of said wall portion, and an outer wall segement having a similar curvature to said inner wall segment, said outer wall segment having stepped flanges formed on the side edges registering upon the side edges of the inner wall segment to maintain said segments in spaced apart relationship thereby defining a chamber therebetween, means to clamp said segments together, and a flexible, resilient membrane clamped by the registering edges of said wall segments and extending between corresponding edges of said halves.
 9. The device according to claim 2 in which said core form includes a substantially curved wall portion between said ends, each of said halves including an inner wall segment having a curvature similar to the curvature of said wall portion, and an outer wall segment having a similar curvature to said inner wall segment, said outer wall segment having stepped flanges formed on the side edges registering upon the side edges of the inner wall segment to maintain said segments in spaced apart relationship thereby defining a chamber therebetween, means to clamp said segments together, said flexible, resilient membrane being clamped by the registering edges of said wall segments and extending between corresponding edges of said halves.
 10. The device according to claim 4 in which said core form includes a substantially curved wall portion between said ends, each of said halves including an inner wall segment having a curvature similar to the curvature of said wall portion, and an outer wall segment having a similar curvature to said inner wall segment, said outer wall segment having stepped flanges formed on the side edges registering upon the side edges of the inner wall segment to maintain said segments in spaced apart relationship thereby defining a chamber therebetween, means to clamp said segments together, said flexible, resilient membrane being clamped by the registering edges of said wall segments and extending between corresponding edges of said halves. 